Electrical condenser



Aug. 17, 1937. J. K. SPRAGUE ELECTRICAL CONDENSER Filed June 28, 1932JUZZAZVK $24612" 1 NVE N TOR.

Patented Aug. 17, 1937 UNITED Ls'rATEs PATENT OFFICE- ELECTRICALCONDENSER chnsetts Application June 28, 1932, Serial No. 619,787

3 Claims.

My invention relates to the construction of electric condensers and to amethod and means for providing connections between the metal foils andthe outer terminals of the condenser.

In condensers of the types most generally used there are provided twometal foils separated from each other by layers of insulating material;the metal foils and the insulating layers being wound together into acompact roll of cylindrical or rectangular shape. For electricalconnection with the metal foils there are to be provided leading-out orterminal wires and while a great number of constructions. have beensuggested and used for this connection, these constructions are eithernot fully satisfactory or are complicated and expensive.

The object of the present invention-is therefore to provide an eiiicientelectrical connection between the metal foils of the condenser and theterminal leads, which is simple and easy to manufacture.

Another object is to provide means to mechanically strengthen the wholecondenser assembly, which means at the same time assist to maintainproper electrical connection between the terminals and their respectivefoils.

A still further object is to provide means, whereby the terminals of thecondenser are reenforced at the point of egress from the condenserassembly andare mechanically connected to the assembly independently oftheir connection with their respective foils.

A further object of the invention is to relieve the connecting pointbetween the terminals and the metal foils from any mechanical stresswhich may be exerted on the free end of the terminal.

A further object of the invention is to provide a novel construction fora compact electrical condenser.

Further objects will appear as the description progresses. a

My invention willbe explained on hand of impregnated paper condensers,but it should be well understood that it is not limited to suchcondensers.

' vertical plane through the lines 3-3 of Fig. 1.

Fig. 4 shows another construction of a conprotective outer shell for thecondenser.

In the drawing forming part of this specificadenser of my invention,with a different method of securing the terminal wires to the condenser.

The condenser Hi illustrated in the drawing, comprises two. strips li-llof aluminum or other suitable metal foil having interposed one or morelayers of paper or other insulating material l2-l2 (two layers beingshown in the drawing). The insulating layers are preferably impregnatedwith a suitable di-electric material, for instance paraffin. The metalfoils with the interposed insulating layers are wound into a roll.

The metal foils il-ll are displaced with respect to their correspondingedges (see Fig. 3) so that the outer edge of one foil extends beyond theinsulating strips to the left as at H, and the outer edge of the otherfoil extends similarly to the right as at l5. There is thus provided ateach end of the condenser an uninsulated edge of each of the foils.While the sheets of the insulating layers l2-l2 are wider than the foilsforming the condenser, they do not extend beyond the edges I4 and i5,but the several sheets i2-l2 align with each other edge for edge.

The outside terminals of the condenser are formed of wires 2l-2l whichmay be for instance copper wires or tin-coated copper wires and are'cutto convenient lengths. The wires 2l-2I are shaped at one end to formcircular loops 22-22 (see Figs. 1 and 3). These loops are connected to'theedges l4 and 15 respectively by means of soldering 23-23. Thereby theloop surrounds the projecting edges l4 and I5 respectively, whichtogether with the solder fill out the whole loop thereby contacting withthe terminal wires 2l-2l on a large area.

The condenser roll is then surrounded by a wrapper i8, preferably ofthin fibre or other similar insulating material, which forms a strongThe width of the wrapper'lii exceeds that of the condenser roll andforms on each end thereof hollow tubular extensions l8-l8.

The extensions l8-I8 surround the loops 22-22; holes l9-I9 beingprovided in the T wrapper through which the terminal wires 2l-2l pass.

The tubular extension l8-i8 is filled out with a suitable compound 25 inplastic or molten state, which upon hardening, substantially contributeto the mechanical strengthening of the condenser and also seals thecondenser against moisture. Furthermore, the compound 25 also greatlystrengthens the connection between the metal foils ll-H and the loops22-22.

On the outer side of the wrapper i9 and surrounding the wires 2i-2l areprovided eyelets 28--2@ which are pressed against the wrapper l6 and thecompound 25 and the wires 2l-2i are 5 soldered to the eyelets at thepoint of egress 213-4 1, whereby mechanical connection of great strengthis established between the terminal wires 2l2i and the condenserassembly.

It should be noted that any mechanical stress 10 or pull exerted on thewires 2 I-2i will be taken up by the whole condenser assembly at the Ipoint 24 without any stress being transmitted to the soldered contactbetween the foils Ii-li and the loops 22-22.

Another form of relieving the joints between the wires 2l-2i and thefoils from mechanical stress, consists of the provision of an auxiliarywrapper l6, as shown in Fig. 4. The wrapper l6 surrounds the condenserproper and is pro- 0 vided near to each end with small holes 20',through which the wires 2l-2l are passed. The holes 20-20' are placedinwardly of the connections between the loops 22-22 and the respectivefoils of the condenser, whereby the 2 wires 2|--2l are bent inwardly andsecurely held by said auxiliary wrapper, after which they pass throughthe main wrapper l6, which is then wound and sealed about the condenserassembly. From the foregoing it should be noted that my inventionprovides for an inexpensive, simipie and compact condenser constructionof great mechanical strength. Furthermore, it provides for a reliableconnection between the metal foils and the outside terminals, whichconnection is altogether relieved of mechanical stress exerted on thefree end of the terminal wire, and at the same time provides for areliable low resistance electrical contact between the metal foil andthe terminal wire.

aoe sco soldered to the extending ends of the metal foils,

and a wrapper of insulating material surrounding said roll and saidlooped ends, holes on said wrapper for the egress of the free ends ofsaid wires, and eyelets surrounding said wires, said eyelets beingsoldered to said terminal wire and being in intimate contact with saidwrapper.

2. An electrical condenser comprising two metal foils and interposedlayers of insulating material wound together to form a roll, said metalfoils having edges extending beyond the insulating layers, terminalwires soldered to said extending edges, and a wrappersurrounding saidcondenser roll and provided with holes for the passage of said wires,and means to fasten said wires to the wrapper at their points of egress.

3. An electrical condenser comprising two metalfoils and interposedlayers of insulating material wound to form. a. roll, each metal foilextending with one edge beyond the insulating layers, and terminal wireshaving looped ends soldered to the extending ends of the foils, awrapper surrounding said roll and extending beyond its two ends, acompound hardened in situ in said extensions and pressing against saidloops, holes in said wrapper for the passage of the terminal wires andeyelets surrounding said wires at their point of egress from thewrapper, said eyelets being in intimate contact with said wrapper andpressing against said compound and being soldered to said wires.

JULIAN K. SPRAGUE.

